Navigation apparatus and method

ABSTRACT

A navigation apparatus and method that store route information, the stored route information including, for each of a plurality of routes starting at a first point and ending at a second point, a required travel time and a traffic condition. The apparatus and method determine whether a guidance route includes the first point and the second point of a stored route. The apparatus and method read out, if a guidance route includes the first point and the second point of a stored route, the stored route information for the stored route that shares the first point and the second point with the guidance route. The read out stored route information having a same or similar traffic condition as a current traffic condition. The apparatus and method output the required time to travel the stored route from the read route information.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2004-203746 filed onJul. 9, 2004 including the specification, drawings and abstract areincorporated herein by reference in their entirety.

BACKGROUND

1. Related Technical Fields

Related technical fields include navigation apparatus.

2. Description of Related Art

Conventional navigation apparatus display a route to a destination andprovide timely guidance, thereby making vehicular travel easier. Thus,the use of such navigation apparatus is increasing.

Conventional navigation apparatus, such as, for example, described inJapanese Unexamined Patent Application Publication No. H9-178501, storea route taken in the past and uses the stored route information whensearching a new route or a detour route. While traveling a route, theconventional navigation apparatus may, for example, select a route takenin the past and set a destination based on the selected route.

SUMMARY

The aforementioned conventional navigation apparatus may receive trafficinformation from an external system, for example, a road trafficinformation communication system, indicating that a traveled guidanceroute is congested. Thus, the apparatus may search a detour route toavoid the congestion. The detour route diverges from the guidance routeat a branch point before the congestion and merges into the originalguidance route again after avoiding the congestion.

However, the searched detour route may not always be the best route toarrive at the destination. For example, when many vehicles choose thesame detour route to avoid the congestion, the detour route may becomecongested. Thus, the detour route may take more time than expected toarrive at the destination.

Even if the conventional navigation apparatus selects a route which hasbeen taken in the past as a detour route, the conventional apparatus isunaware of a traffic condition ahead on the detour route. Thus, theconventional apparatus is unable to determine the best detour routebased on traffic congestion.

Accordingly, it is beneficial to provide a navigation apparatus that maydetermine the best detour route based on traffic congestion.

Accordingly, various exemplary implementations of the principlesdescribed herein provide a navigation apparatus including a controller.The controller stores route information, the stored route informationincluding, for each of a plurality of routes starting at a first pointand ending at a second point, a required travel time and a trafficcondition. The controller determines whether a guidance route includesthe first point and the second point of a stored route. The controllerreads out, if a guidance route includes the first point and the secondpoint of a stored route, the stored route information for the storedroute that shares the first point and the second point with the guidanceroute. The read out stored route information having a same or similartraffic condition as a current traffic condition. The controller outputsthe required time to travel the stored route from the read routeinformation.

Various exemplary implementations of the principles described hereinprovide a navigation apparatus including a controller. The controllergenerates route information, the route information including, for eachroute, a required time to travel the route, traffic conditions for theroute, and traffic conditions of other routes having a same first pointand second point as the route, the route information generated each timethe route is traveled. The controller stores the generated routeinformation.

Various exemplary implementations of the principles described hereinprovide a navigation apparatus for storing a detour route that divergesfrom a branch point on the guidance route and merges into the guidanceroute at a junction point, including a controller. The controllerreceives current traffic conditions from an external system. Thecontroller stores path information for a path, the path being a segmentof the guidance route from the branch point to the junction, the pathinformation including a first required time to travel the path, atraffic condition of the path, and a traffic condition of the detourroute. The controller stores detour route information for the detourroute, the detour route information including a second required time totravel the detour route, a traffic condition of the path, and a trafficcondition of the detour route. The controller reads out, when arrivingat the branch point, path information having a same or similar trafficcondition as a current path traffic condition and detour routeinformation having a same or similar traffic condition as a currentdetour route traffic condition. The controller outputs at least one ofthe read out first required time, the read out second required time, thepath, and the detour route, on a display unit.

Various exemplary implementations of the principles described hereinprovide a navigation method. The method includes storing routeinformation, the stored route information including, for each of aplurality of routes starting at a first point and ending at a secondpoint, a required travel time and a traffic condition. The methodincludes determining whether a guidance route includes the first pointand the second point of a stored route. The method includes reading out,if a guidance route includes the first point and the second point of astored route, the stored route information for the stored route thatshares the first point and the second point with the guidance route. Theread out stored route information having a same or similar trafficcondition as a current traffic condition. The method includes outputtingthe required time to travel the stored route from the read routeinformation.

Various exemplary implementations of the principles described hereinprovide a navigation method. The method including generating routeinformation, the route information including, for each route, a requiredtime to travel the route, traffic conditions for the route, and trafficconditions of other routes having a same first point and second point asthe route, the route information generated each time the route istraveled; and storing the generated route information.

Various exemplary implementations of the principles described hereinprovide a navigation method for storing a detour route that divergesfrom a branch point on the guidance route and merges into the guidanceroute at a junction point. The method including receiving currenttraffic conditions from an external system; storing path information fora path, the path being a segment of the guidance route from the branchpoint to the junction, the path information including a first requiredtime to travel the path, a traffic condition of the path, and a trafficcondition of the detour route; storing detour route information for thedetour route, the detour route information including a second requiredtime to travel the detour route, a traffic condition of the path, and atraffic condition of the detour route; reading out, when arriving at thebranch point, path information having a same or similar trafficcondition as a current path traffic condition and detour routeinformation having a same or similar traffic condition as a currentdetour route traffic condition; and outputting at least one of the readout first required time, the read out second required time, the path,and the detour route, on a display unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary implementations will now be described with reference to theaccompanying drawings, wherein:

FIG. 1 is a block diagram showing a navigation apparatus according to anexemplary implementation of the principles described herein;

FIG. 2 shows a guidance screen according to an exemplary implementationof the principles described herein;

FIG. 3 shows a method of creating path information and detour routeinformation according to an exemplary implementation of the principlesdescribed herein;

FIG. 4 shows a method of creating path information and detour routeinformation according to an exemplary implementation of the principlesdescribed herein;

FIG. 5 shows a method of creating detour route information according toan exemplary implementation of the principles described herein; and

FIG. 6 shows route guidance method according to an exemplaryimplementation of the principles described herein.

DETAILED DESCRIPTION OF EXEMPLARY IMPLEMENTATIONS

FIG. 1 shows a navigation apparatus 1, for example, installed in avehicle. The navigation apparatus 1 may include a data input/output unit2, a current position detector 3, a traffic information receiver 4, amemory 5, a controller 6, and am memory 6 a. The controller 6 may beconnected with the data input/output unit 2, the current positiondetector 3, the traffic information receiver 4, and/or the memory 5, andmay controls the data input/output unit 2, the current position detector3, the traffic information receiver 4, and//or the memory 5.

The data input/output unit 2 may include, for example, a various kindsof operation buttons. The data input/output unit 2 may output variouskinds of operation signals to the controller 6 to perform routeguidance. In addition, the data input/output unit 2 may include adisplay unit 2 a. The display unit 2 a may include, for example, aliquid crystal display and may display graphics to execute routeguidance. The display unit 2 a may include a display medium including atouch panel switch function. Various kinds of operation signals forroute guidance may be output to the controller 6 by touching anoperation switch on the screen.

The current position detector 3 may detect a current location of thevehicle in which the navigation apparatus 1 is installed. The currentposition detector 3 may include, for example, a GPS (Global PositioningSystem), a vehicle speed sensor, and a direction sensor, and outputvarious kinds of signals to the controller 6 to calculate a currentposition of the vehicle.

The traffic information receiver 4 may include a receiving unit forreceiving traffic information distributed from an external road trafficinformation communication system. The traffic information receiver 4 mayoutput the received traffic information to the controller 6. The trafficinformation may include traffic condition information such as, forexample, information about a degree of congestion. Such trafficinformation may be used to determine the traffic congestion on a link ona route. The traffic information receiver 4 may receive the trafficinformation and output it to the controller 6.

As used herein, the term “link” refers to, for example, a road orportion of a road. For example, according to one type of road data, eachroad may consist of a plurality of componential units called links. Eachlink may be separated and defined by, for example, an intersection, anintersection having more than three roads, a curve, and/or a point atwhich the road type changes.

The memory 5 may be physically, functionally, or conceptually dividedinto a path portion 11, a detour route portion 12, a map data portion13, a search data portion 14, and/or a program data portion 15. The pathportion 11 may store path information about a part of a route. Thedetour route portion 12 may store detour information about a part of aroute. As used herein a “detour route” is a route that diverges from aguidance route set by a user at a branch point as a first point on theguidance route and merges into the guidance route at a junction as asecond point on the guidance route.

Path information may include a required time (hereinafter referred to asa first required time) for traveling from the first point to the secondpoint along the guidance route. The path information may include atraffic condition on the path when the vehicle travels on the path and atraffic condition on the detour route corresponding to the path. Forexample, the traffic condition may be “crowded,” “congested,” or“not-congested” obtained from the road traffic information communicationsystem.

The detour route information may include a required time to travel adetour route (hereinafter referred to as a second required time). Thedetour route information may include the traffic condition on the detourroute when the vehicle travels on the detour route and a trafficcondition on the path corresponding to the detour route. Again, forexample, the traffic condition may be “crowded,” “congested,” or“not-congested” obtained from the road traffic information communicationsystem.

The map data portion 13 may store various kinds of data, such as, forexample, destination data and map data. The various kids of data may beused for, for example, map display, route guidance, destination setting,address search, and/or telephone number search. The search data portion14 may store, for example, road data and fixed vehicle speed data used,for example, for route searching.

The program data portion 15 may store various kinds of instructions anddata for performing, for example, route search and route guidance. Theprogram data portion 15 may store a program, for example, for creatingand storing path information in the path portion 11 and detour routeinformation in the detour route portion 12. The program data portion 15may store a program for executing route guidance by using the pathinformation and the detour route information.

The controller 6 may control various kinds of route guidance such as,for example, route searching, route detecting, route informationcreation, and route guidance, for example, based on instructions storedin the program data portion 15.

During route searching, for example, a current position may be foundbased on a detection signal from the current position detector 3. Thecurrent position may be displayed on a map, for example, on the displayunit 2 a based on the various kinds of data, such as, for example, mapdata stored in the map data portion 13. A destination, for example,input by a user operating the data input/output unit 2 may displayed onthe map displayed in the display unit 2 a.

During route detection, for example, a route connecting two points maybe searched based on, for example, road data stored in the search dataportion 14. The route may be detected by user operation of the datainput/output unit 2 or automatically.

Route information may be created, for example, during traveling. Forexample, when the vehicle travels along a detour route, which divergesfrom the guidance route at a branch point and merges into the guidanceroute again at a junction, the detour route information may be createdand stored in the detour route portion 12 upon the arrival at thejunction. When the vehicle travels along a path from the branch point tothe junction, the path information may be created and stored in the pathportion 11 upon the arrival at the junction.

During route guidance, when traveling along the guidance route, achanging current position with time may displayed, for example, in themap on the screen. Further, the user may be given an audio guidanceconcerning the changing current position. During route guidance, whenarriving at the branch point, guidance may be provided along theguidance route (the path) or guidance may be provided along the detourroute, for example, based on the path information in the path portion 11or the detour route information in the detour route portion 12.

For example, a guidance screen G may be displayed on the display unit 2a as shown in FIG. 2 upon arrival at the branch point. If a detour routefor the current guidance route (the current path) is searched at thebranch point, each required time (e.g., a first required time for thepath and a second required time for the detour route) to travel to thejunction may be displayed on the guidance screen G.

Next, an exemplary method for creating path information and detour routeinformation, will be described with reference to FIGS. 3 and 4. Theexemplary method may be executed, for example, by the controller 6 ofthe above described navigation apparatus 1. However, it should beappreciated that the exemplary method need not be limited by the abovestructure. First, a processing for creating path information and detourroute information and for storing the information, or example, in thepath portion 11 and the detour route portion 12 will be described.

For the purpose of this example, as shown in FIG. 3, it is assumed thatthere is a vehicle traveling from a current position P to a destinationalong a guidance route R1. The guidance route R1 may be displayed, forexample, on the display unit 2 a of the navigation apparatus 1.

As shown in FIG. 4, first, a detour route that diverges from theguidance route R1 and merges into the R1 again is searched for from anext branch point N1 (Step S10). The search may be performed, forexample, by the controller 6. The search may begin, for example, up to700 meters before a branch point N1. If no detour route is found (StepS12=NO), the method returns to step S10 and a detour route is searchedat a next branch point.

If a detour route that merges into the guidance route R1 is found (StepS12=YES), the detour route R1 b and the path R1 a may be temporarilystored (Step S14). For example, the controller 6 may temporarily store apart of the guidance route R1, from the branch point N1 to a junction N2at which the detour route R1 b merges into the guidance route R1, as apath R1 a in the memory 6 a.

Next, it is determined whether the current position is within 700 metersof the branch point N1 (Step S16). The determination may be made, forexample, by the controller 6. If the current position is within 700meters of the branch point N1 (Step S16=YES), traffic information isobtained for the path R1 a and the detour route R1 b (Step S18). Thetraffic information may be obtained, for example, from the road trafficinformation communication system via the traffic information receiver 4.Specifically, the controller 6 may obtain a traffic condition (crowded,congestion, or non-congestion) on the path R1 a and traffic condition(crowded, congestion, or non-congestion) on the detour route R1 b amongaccumulated traffic information.

Subsequently, the two traffic conditions on the path R1 a and the detourroute R1 b are stored (Step S20), for example, by the controller 6 inthe memory 6 a. Next, it is determined whether the branch point N1 hasbeen passed through (Step S22). This determination may be made, forexample, by the controller 6. The vehicle may pass through the branchpoint N1, for example, by traveling along the path R1 a or the detourroute R1 b. Therefore, when it is determined that the branch point N1has been passed through (Step S22=YES), the date and time when thebranch point N1 has been passed through are temporarily stored (StepS24), for example, in the memory 6 a under control of the controller 6.

It is then determined whether a junction point N2 is passed (Step S26).For example, when the vehicle arrives at and further passes through thejunction N2 (Step S26=YES), the junction passing time is stored (forexample, in the memory 6 a) and along with the route (e.g., the path R1a or the detour route R1 b) that was traveled from the branch point N1to the junction point N2. Next, the required time to travel thespecified route is calculated and temporarily stored (Step S28), forexample in the memory 6 a. For example, if the path R1 a was taken, arequired time to travel along the path based on the passing time at thebranch point N1 and the passing time at the junction point N2 iscalculated. The required time for the path R1 a may be referred to as afirst required time. On the other hand, if the detour route R1 b wastaken, the required time is calculated based on the passing time at thebranch point N1 and the passing time at the junction point N2. Terequired time for the detour R1 b may be called a second required time.

After the first required time or the second required time is calculated,route information is created including the calculated required time,traffic conditions (for example, stored in the memory 6 a), and thepassing date and time (Step S30). For example, if the first requiredtime for the path R1 a is calculated, the controller 6 may create pathinformation for the path R1 a including the first required time, thepassing date and time at the branch point N1, and both trafficconditions on the path R1 a and the detour route R1 b at the passingtime. Then, the controller 6 may stores the created information in thepath portion 11. Similarly, for example, if the second required time forthe detour route R1 b is calculated, the controller 6 may create detourroute information for the detour route R1 b including the secondrequired time, the passing date and time at the branch point N1, andboth traffic conditions on the path R1 a and the detour route R1 b atthe passing time. Then, the controller 6 may store the createdinformation in the detour route portion 12.

When the junction point N2 is passed through, a required time to travela selected route, traffic condition on the traveled route, trafficcondition on the other route which has not been traveled, and thepassing date and time at the branch point N1 are stored as routeinformation for the traveled route.

If the vehicle travels along the path R1 a, the first required time,traffic conditions on both of the path R1 a and the detour route R1 b,and the passing date and time at the branch point N1 are stored as thepath information in the path portion 11. If the vehicle travels alongthe detour route R1 b, the second required time, traffic conditions onboth of the path R1 a and the detour route R1 b, and the passing dateand time at the branch point N1 are stored as the detour routeinformation in the detour route portion 12.

Once either of the route information is created, the method isterminated and, for example, the method may be repeated to create nextroute information. For example, when arriving at the branch point N1during traveling along the guidance route R1, the more times the path R1a and the detour route R1 b are taken, the more number of pathinformation and detour route information are stored in the path portion11 and the detour route portion 12. Thus, path information and detourroute information including a same or similar traffic condition to thetraffic condition at the time may be obtained at the branch point N1 atany given time.

Next, another exemplary method of creating detour route information willbe described with reference to FIG. 5. The exemplary method may beexecuted, for example, by the controller 6 of the above describednavigation apparatus 1. However, it should be appreciated that theexemplary method need not be limited by the above structure.

In this method, a detour route is not searched in advance to create pathinformation and detour route information. Rather, if a user selects aroute that diverges from a guidance route and merges into the guidanceroute again, that route may be used to create the route information (thedetour route information in this case). The exemplary method may be, forexample, executed by operating an operation button of the datainput/output unit 2 to change a mode, or may be executed automatically.

Again, as shown in FIG. 3, it is assumed that there is a vehicletraveling from a current position P to a destination along a guidanceroute R1. The current position P and guidance route R1 may be, forexample, displayed on the display unit 2 a of the navigation apparatus1. First, it is determined whether the guidance (Step S40) has beenterminated (Step S41). If guidance is terminated (Step S41=YES), forexample, the vehicle has arrived at the destination, the method ends.Otherwise (Step S41=NO), it is determined whether the vehicle istraveling on a route that has diverged from the guidance route R1 whileexecuting route guidance (Step S42).

If the taken route diverges from the guidance route R1 (Step S42=YES),received traffic information is stored (Step S44), for example, in thememory 6 a, beginning at the diverging point (the branch point N1). Forexample, the controller 6 may store traffic information from the roadtraffic information communication system concerning all routes within apredetermined area of the center of the diverging point (the branchpoint N1) in the memory 6 a. Then, the position of the diverging point(the branch point N1) and the passing time at the diverging point arestored (Step S46), for example, in the memory 6 a.

Next it is determined whether the guidance (S48) has been terminated(Step 49). If guidance is terminated (Step S49=YES), the method ends.Otherwise (Step S49=NO), it is determined whether the route on which thevehicle is currently traveling has merged into the guidance route R1,again while executing route guidance (Step S50). When the travelingroute merges into the guidance route R1 (Step S50=YES), the position ofthe merge point (junction point N2) and the passing time at the junctionpoint N2 are stored (Step S52), for example, in the memory 6 a.

Then, a path R1 a from the branch point N1 to the junction point N2 onthe guidance route R1 is specified based on the junction N2, and trafficinformation for the path R1 a is determined. The determined trafficinformation is stored as the traffic condition of the path R1 a (StepS54), for example, in the memory 6 a. A detour route R1 b that has beentaken by the vehicle from the branch point N1 on the guidance route R1to the junction point N2 is specified. The traffic condition of thedetour route R1 b is determined (for example, from all stored routetraffic information in the memory 6 a) and stored as the trafficcondition of the detour route R1 b (Step S54), for example, in thememory 6 a.

The time required to travel the detour route R1 b (second required time)is calculated based on the passing time at the branch point N1 and thepassing time at the junction point N2 (Step S56). After the secondrequired time is calculated, the detour route information, including thesecond required time and traffic conditions on both of the path R1 a andthe detour route R1 b, are stored in the detour route portion 12 (StepS58) the method may be repeated to create next detour route information(Step S40).

According to the exemplary method shown in FIG. 5, although pathinformation for the path R1 a is not created, the user initiated detourroute information for the detour route R1 b may be created. Although,according to the exemplary method, a passing date is not stored, thepassing date may be included in the detour route information.

Next, a route guidance, for example, based on path information for eachpath stored in the path portion 11 and detour route information for eachdetour route in the detour route portion 12, will be described withreference to FIG. 6. The exemplary method may be executed, for example,by the controller 6 of the above described navigation apparatus 1.However, it should be appreciated that the exemplary method need not belimited by the above structure.

Once again, it is assumed that there is a vehicle traveling from acurrent position P to a destination along a guidance route R1, forexample, displayed on the display unit 2 a of the navigation apparatus1.

According to the exemplary navigation method, it is determined whether adetour route R1 b that diverges from the guidance route R1 at a branchpoint N1 and merges into the guidance route R1 again exists before thevehicle arrives at a the branch point N1 (for example, 700 meters beforethe closest branch point) (Step S60). For example, detour routeinformation for each detour route stored in the detour route portion 12is searched to determine if such a route exists (Step S62). If there isno detour route R1 b (Step S62=NO), the method returns to Step S60, andnext detour route is searched at next branch point.

If at least one detour route R1 b exists (Step S62=YES), the detourroute information for the searched detour route(s) R1 b is stored (StepS64), for example in memory 6 a. Next path information for a path R1 acorresponding to the searched detour route R1 b from the path portion 11is read out and temporarily stored (Step S66). It is assumed here thatone or more than one path information of the path R1 a corresponding tothe detour route R1 b are read out.

It is then determined whether the current position of the vehicle iswithin 700 meters of the branch point N1 (Step S68). If the vehicle iswithin 700 meters of the branch point N1 (Step S68=YES), trafficinformation is obtained (Step S70), for example, from the road trafficinformation communication system via the traffic information receiver 4.Specifically, for example, the controller 6 may obtain a trafficcondition on the path R1 a and a traffic condition on the detour routeR1 b from the stored traffic information.

Path information corresponding to the path R1 a and detour routeinformation corresponding to the detour route R1 b is read out havingsame or similar traffic condition pattern to the obtained currenttraffic condition on the path R1 a and the obtained current trafficcondition on the detour route R1 b, form among the various stored pathinformation and detour route information (Step S74).

In this example, a same pattern or a similar pattern is intended toencompass at least following. For example, when a current trafficcondition on the path R1 a is “crowded” and a current traffic conditionon the detour route R1 b is “congested,” a stored traffic condition onthe path R1 a that is “crowded” and a stored traffic condition on thedetour route R1 b that is “congested” may be considered similarpatterns. According to detour route information, a stored trafficcondition on the path R1 a that is “congested” and a stored trafficcondition on the detour route R1 b that is “congested” may be consideredsimilar as well. Thus, the current traffic condition and stored trafficcondition need not be identical. An acceptable degree of similarity maybe determined in advance.

In this example, according to the path information, the trafficcondition pattern on the current path R1 a is the same as the trafficcondition pattern on the detour route R1 b. On the other hand, accordingto the detour route information, the traffic condition pattern on thecurrent path R1 a is a similar pattern to the traffic condition patternon the detour route R1 b.

Next, based on the read path information and the read detour routeinformation, a picture may be displayed to the user, for example, on thedisplay unit 2 a to prompt the user to select either of the path R1 a orthe detour route R1 b to arrive at the junction point N2 (Step S76).

FIG. 2 shows an example of a guidance screen G that may be displayed onthe display unit 2 a. The guidance screen G may show each required time,(the first required time to travel the path R1 a from the branch pointN1 to the junction point N2 and the second required time to travel thedetour route R1 b from the branch point N1 to the junction point N2).The user may select either of the path or the detour route to travelbased on the guidance screen G.

The first required time in the path information based on a same orsimilar traffic condition pattern to the current traffic condition onthe path and the second required time in the detour route informationbased on a same or similar traffic condition pattern to the currenttraffic condition on the detour route (for example, determined in StepS74) may be displayed as the required times for the route R1 a and forthe route R1 b. Thus, accurate required times may be displayed andsuitable route guidance may be executed.

The aforementioned exemplary implementations of the principles describedherein may be considered advantageous in at least the followingrespects.

According to the exemplary implementations, when a vehicle arrives at abranch point, the controller 6 may out a required time (first requiredtime) that has been taken to travel a path R1 a in the past on the basisof same or similar traffic condition patterns to the current trafficcondition patterns of the path R1 a and a detour route R1 b, from thepath portion 11. In addition, the controller 6 may read out a requiredtime (second required time) that has been taken to travel the detourroute R1 b in the past on the basis of same or similar traffic conditionpatterns to the current traffic condition patterns of the path R1 a andthe detour route R1 b, from the path information storage unit 12.

Even if when traffic condition patterns on the path R1 a and the detourroute R1 b change while the route R1 is being traveled, the firstrequired time and the second required time are determined on the basisof same or similar traffic condition patterns are displayed on thedisplay unit 2 a by the controller 6. Thus, the user may know whichroute should be selected to get a junction point first with a highdegree of accuracy and a most suitable route guidance may be executed.

The controller 6 may create and store path information once the vehicletravels along the path R1 a. Similarly, the controller 6 may create andstore detour route information once the vehicle travels along the detourroute R1 b. Therefore, a large amount of information may be storedeasily and accurate route guidance may be executed.

Even if the user selects a route that diverges from the guidance routeR1 at the branch point N1 and merges into the route at the junction N2again, on his/her own will, the controller 6 may creates and stores thetimely detour route information once the vehicle travels along thedetour route R1 b. Thus, a large amount of information may be storedeasily and accurate route guidance may be executed.

The traffic information receiver 4 may receive traffic conditions onboth of the path R1 a and the detour route R1 b from the road trafficinformation communication system. Thus, accurate traffic information maybe obtained with simple operation.

Note that, various other exemplary implementations may differ from theabove described exemplary implementations in at leas the followingrespects.

In the aforementioned exemplary implementations, traffic conditionpatterns may include three types of traffic conditions, including“crowded,” “congested,” and “not congested.” However, various otherinformation including, for example, time zone, date, season, or weathermay be added as traffic conditions. Thus, more accurate information maybe obtained and accurate route guidance may be executed.

In the aforementioned exemplary implementations, for ease ofexplanation, two routes, a path and a detour route, are described.However, the principles of the exemplary methods equally apply if two ormore routes connecting a first point and a second point exist.

In the aforementioned exemplary implementation, current trafficconditions are obtained just before arriving at a branch point andguidance of either of a path or a detour route is operated based on theobtained traffic condition. However, it is possible to obtain trafficconditions at any point before the branch point as traffic conditions onthe path and the detour route. Thus, at the point much before the branchpoint, the user may know existence of detour routes and may select oneroute by a displayed guidance, well before reaching the branch point,such as for example, when beginning a trip.

In the aforementioned exemplary implementation, when the vehicle arrivesat the branch point N1, a required time to travel the path R1 a and therequired time to travel the detour route R1 b are displayed on theguidance screen G in FIG. 2. However, only the shorter required time maybe displayed on the display unit 2 a. In addition, instead of suchrequired time, a difference between the required time (first requiredtime) for the path R1 a and the required time (second required time) forthe detour route R1 b may be found and displayed on the display unit 2a, or even displayed with voice guidance. For example, a guidance aboutthe time difference, such as, “This route requires 10 minutes less,” maybe provided.

In the aforementioned exemplary implementation, the required time forthe path R1 a and the required time for the detour route R1 b aredisplayed on the guidance screen G. However, the path R1 a and thedetour route R1 b may be displayed on the map together with the guidanceroute R1, the first required time, and the second required time. In thiscase, the path R1 a and the detour route R1 b may be indicated, forexample, by different colors from other routes or by blinking lines.

In the aforementioned exemplary implementation, the first required timeand the second required time are displayed. However, current trafficcondition, the date of collecting the first required time and the secondrequired time (that is, the date of traveling by the vehicle in thepast), and the traffic condition at that time may be displayed as well.Such information may make the user more comfortable in selecting a mostsuitable route because the user may have more information for making adecision.

While various features have been described in conjunction with theexamples outlined above, various alternatives, modifications,variations, and/or improvements of those features and/or examples may bepossible. Accordingly, the examples, as set forth above, are intended tobe illustrative. Various changes may be made without departing from thebroad spirit and scope of the underlying principles.

1. A navigation apparatus for storing and using information about adetour route that diverges from a branch point on the guidance route andmerges into the guidance route at a junction point, comprising: a memorythat: stores path information for a path each time the path is traveled,the path being a segment of the guidance route from the branch point tothe junction, the path information including a first required time totravel the path, a traffic condition of the path at the time the path istraveled, and a traffic condition of the detour route at the time thepath is traveled; and stores detour route information for the detourroute each time the detour route is traveled, the detour routeinformation including a second required time to travel the detour route,a traffic condition of the path at the time the detour route istraveled, and a traffic condition of the detour route at the time thedetour route is traveled; and a controller that: receives currenttraffic conditions from an external system; reads out, when arriving atthe branch point, path information having a same or similar storedtraffic condition as a current path traffic condition and detour routeinformation having a same or similar stored traffic condition as acurrent detour route traffic condition; and outputs informationindicating the read out first required time, the read out secondrequired time, and the existence of the detour route, on a display unit.2. The navigation apparatus of claim 1, wherein the controller:calculates the first required time to travel the path; determines thecurrent traffic condition of the path, and the current traffic conditionof the detour route based on the current traffic conditions receivedfrom the external system; creates the path information; stores thecreated path information a memory; calculates the second required timeto travel the detour route; creates the detour route information; andstores the created detour route information in the memory.
 3. Thenavigation apparatus of claim 1, wherein the controller: determines, atthe branch point, whether the guidance route is being traveled; stores,if it is determined at the branch point the guidance route is no longerbeing traveled, the received current traffic information; determines, atthe junction point, whether the guidance route is being traveled;obtains, if it is determined at the branch point the guidance route isno longer being traveled and it is determined at the junction point thatthe guidance route is being traveled, the current traffic condition ofthe detour route and the current traffic condition of the path based onthe received traffic conditions; creates the detour route information,the detour route information including the obtained current trafficcondition of the detour route, the obtained current traffic condition ofthe path, and the second required time to travel the detour route; andstores the detour route information.
 4. The navigation apparatus ofclaim 1, wherein the path information is stored every time the path istraveled.
 5. The navigation apparatus of claim 1, wherein the detourroute information is stored every time the detour route is traveled. 6.A navigation method for storing and using information about a detourroute that diverges from a branch point on the guidance route and mergesinto the guidance route at a junction point, comprising: storing pathinformation for a path each time the path is traveled, the path being asegment of the guidance route from the branch point to the junction, thepath information including a first required time to travel the path, atraffic condition of the path at the time the path is traveled, and atraffic condition of the detour route at the time the path is traveled;storing detour route information for the detour route each time thedetour route is traveled, the detour route information including asecond required time to travel the detour route, a traffic condition ofthe path at the time the detour route is traveled, and a trafficcondition of the detour route at the time the detour route is traveled;receiving current traffic conditions from an external system; readingout, when arriving at the branch point, path information having a sameor similar stored traffic condition as a current path traffic conditionand detour route information having a same or similar stored trafficcondition as a current detour route traffic condition; and outputtinginformation indicating the read out first required time, the read outsecond required time, and the existence of the detour route, on adisplay unit.
 7. The navigation method of claim 6, further comprising:calculating the first required time to travel the path; determining thecurrent traffic condition of the path, and the current traffic conditionof the detour route based on the current traffic conditions receivedfrom the external system; creating the path information; storing thecreated path information a memory; calculating the second required timeto travel the detour route; creating the detour route information; andstoring the created detour route information in the memory.
 8. Thenavigation method of claim 6, further comprising: determining, at thebranch point, whether the guidance route is being traveled; storing, ifit is determined at the branch point the guidance route is no longerbeing traveled, the received current traffic information; determining,at the junction point, whether the guidance route is being traveled;obtaining, if it is determined at the branch point the guidance route isno longer being traveled and it is determined at the junction point thatthe guidance route is being traveled, the current traffic condition ofthe detour route and the current traffic condition of the path based onthe received traffic conditions; creating the detour route information,the detour route information including the obtained current trafficcondition of the detour route, the obtained current traffic condition ofthe path, and the second required time to travel the detour route; andstoring the detour route information.
 9. The navigation method of claim6, further comprising storing the path information every time the pathis traveled.
 10. The navigation method of claim 6, further comprisingstoring the detour route information every time the detour route istraveled.
 11. A computer-readable storage medium storing a set ofprogram instructions executable on a data processing device and usableto store and use information about a detour route that diverges from abranch point on the guidance route and merges into the guidance route ata junction point, the program comprising: instructions for storing pathinformation for a path each time the path is traveled, the path being asegment of the guidance route from the branch point to the junction, thepath information including a first required time to travel the path, atraffic condition of the path at the time the path is traveled, and atraffic condition of the detour route at the time the path is traveled;instructions for storing detour route information for the detour routeeach time the detour route is traveled, the detour route informationincluding a second required time to travel the detour route, a trafficcondition of the path at the time the detour route is traveled, and atraffic condition of the detour route at the time the detour route istraveled; instructions for receiving current traffic conditions from anexternal system; instructions for reading out, when arriving at thebranch point, path information having a same or similar stored trafficcondition as a current path traffic condition and detour routeinformation having a same or similar stored traffic condition as acurrent detour route traffic condition; and instructions for outputtinginformation indicating the read out first required time, the read outsecond required time, and the existence of the detour route, on adisplay unit.